Supercritical fluids (SCF), have received, and continue to receive attention. Briefly defined, a supercritical fluid is a gas, subjected to temperatures and pressures over limits known as Critical Pressure (Pc), and Critical Temperature (Tc). Above these points, the SCFs have different properties than they possess in the gaseous state. FIG. 1 shows a graph of supercritical conditions for one gas, CO.sub.2 Different conditions are necessary to form other supercritical fluids, as may be seen, e.g., in Table 7, infra.
One property typical of SCFs is increased solvation power. It is known that, at temperatures and pressures above Pc and Tc, the SCFs extract materials otherwise removable only by toxic, prohibitively expensive, or inefficient means. For example, various chemical solvents, such as chloroform and methanol have been used. While the use of these products does give good results, the concern is, and has been, that residues of the solvent are either toxic per se or are promoters of diseases (e.g., they may be carcinogenic).
SCF extraction has been particularly useful for obtaining aromatic and lipid components from plant tissues. For example, the oil industry relies extensively on processes by which vegetable oils, such as soybean, cottonseed and corn oils, are removed from their vegetative components. The coffee industry uses supercritical processes for removing caffeine from coffee, and flavor extraction using SCFs has been applied to, e.g., hops, vegetables, fruits (lemons), and spices. As might be expected from the use of SCFs as flavor extractors, they have been used to extract fragrances as well.
It is important to note that, while SCFs have been and are used extensively for vegetable and seed extraction, no one has used the process for extraction of components from animal materials, such as organs, tissues, or cells.
It is desirable to have an effective method of extraction for animal tissues, because of the usefulness of the material obtained. Just in the field of lipid containing molecules, animal tissues contain angiogenic factors, hormones, regulatory molecules, and so forth. Lipid rich organs, such as liver, brain, kidney, and epithelial tissues, are rich sources of necessary and desirably biological products. A method of extracting these, via supercritical processes, has been heretofore lacking.
Hence it is an object of this invention to provide a method of obtaining desired components of animal tissues, cells, and organs, using supercritical fluids.
It is a further object of the invention to obtain complex and simple animal derived lipid containing materials by supercritical processes.
It is a still further object of this invention to obtain amino acid, nucleotide, saccharide containing materials as well as other molecules, using supercritical processes.
How these and other objects of the invention are achieved will be seen by reviewing the materials which follow.